The present invention generally relates to a positively obtained fold arrangement of a folding-top covering for a folding top, and more particularly to a fold arrangement which has the least adverse effect on the dimensions of a storage box for the folding top while protecting against the formation of creases in the folding-top covering.
A fold arrangement of this type is disclosed by German Patent Specification 3,726,430, wherein the fold arrangement extends over the entire roof width in the region of a flexible rear window of a convertible top.
So that the intended fold arrangement forms automatically when the folding top is opened, the folding-top covering is stiffened in the region of a round-bending fold, on both sides of the rear window, by four leaf-spring elements. These leaf-spring elements extend transversely relative to a bending or folding axis of the round-bending fold and are held in a common tubular belt on the rear face of the folding-top covering. At a distance from the ends of the leaf-spring elements, in a second tubular belt, a rubber band is fastened, at its ends, to the folding-top covering and is prestressed as a result of longitudinal stretching.
The bending elasticity of the leaf-spring elements and the compression tension of the rubber band are so coordinated with one another that, when the folding top is opened, the surface region of the folding-top covering stiffened by the leaf-spring elements is deformed under the compression force of the rubber band so as to form a round-bending fold.
When the folding top is in the process of being closed, the round-bending fold is redeformed by longitudinal tensioning forces in the folding-top covering, the leaf-spring elements resuming their straight extended position. The leaf-spring elements, because they extend over the width of the round-bending fold, ensure that, when the folding top is stowed away, no sharp creases can occur in the folding-top covering which give the folding-top fabric an unsightly appearance even after only a short period of service. Since the rear window acts as a surface stiffening of the folding-top covering, the outwardly curved round-bending fold at the same time assists in the formation of an inwardly curved connecting bending fold.
Protection against sharp creases in the surface of the connecting bending fold is also afforded to a certain extent by the elastic behavior of the rear window. However, for this, the bending radius of the connecting bending fold has to be made large and has to be maintained even when the folding top is retracted.
Even though the middle region of the folding-top box, assigned for storing to the folding top, may have a sufficient accomodation space for a bending folding of the folding-top covering with a large radius of curvature, this will scarcely be available in the side-wall region of the folding top.
Since the folding-top covering has to be stowed away in the side-wall plane between the side-wall structure parts, transferring the above-noted round-bending fold principle to the side wall of the folding-top covering would require a considerable widening of the lateral legs of the folding-top box, thus reducing the seat width of a rear-seat bench.
In particular, guiding the folding-toP fabric closely round the side-wall structure parts would not be directly possible because of the rubber band stretched on the inside of the folding-top covering. Also, the leaf-spring elements cannot be shortened as required, and therefore even an accumulation of a plurality of round-bending folds with a relatively small fold depth can scarcely be obtained according to the above-noted functional principle.
These problems arise to an even greater extent when the side-wall regions of the folding-top covering are extremely long, as occurs, for example, in the folding top disclosed by German Patent Specification 3,724,532. During the operation of retracting this folding top, beyond the existing length of the folding-top covering in the side-wall region, there is also a shifting movement of the fabric-holding bar retaining the folding-top fabric in the rear circumferential region, accompanied by a reduction in length of a lateral leg of the fabric-holding bar.
As a result, the folding-top fabric cannot be secured over an entire side-wall length, and therefore it has to be stiffened considerably in the region of its unsecured length. This leads, during folding, to an uneven distribution of the folding resistance over the height of the side-wall surface of the folding-top covering.
For the reasons explained, an object on which the invention is based is to improve a fold arrangement of the relevant generic type, to the effect that it has the least possible adverse effect on the dimensions of the folding-top box assigned to the folding top, whilst protection against the formation of creases is to be maintained.
The solution according to preferred embodiments of the present invention for achieving this object and other object emerges from the use of reinforcing measures, taken on a folding top covering, which allow for a relatively shape bending of the round-bending fold. Because of improved flexibility, the round-bending fold or a plurality of round-bending folds extending next to one another can be folded relatively flat, without creases occurring. The top can thereby be stowed, in extremely space-saving way, close next to structure parts of the folding-top structure.
Preferably, the round-bending fold is stiffened by means of measures which, in any case, are necessary in terms of construction or stylistically desirable.
An especially flat round-bending fold is obtained if the round-bending fold is drawn into an S-shaped form by pulling means, since the tension band can thereby rest supportively over its entire length against the folding-top covering on the wide side.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.